Cooling method and cooling equipment of extruded article

ABSTRACT

A part of outer circumference of an extruded article that is difficult to be cooled is selectively pre-cooled by a pre-cooler ( 18 ) and is cooled by a cooling fan ( 17 ) by forcible air-cooling and the temperature of the portion that is difficult to be cooled becomes lower than the other portion, so that the outer circumference is not cooled in an imbalanced manner during subsequent forcible air-cooling process, thereby avoiding bent of the extruded article.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a method and an equipment for cooling an extruded article molded by hot-extruding metal material such as aluminum and aluminum alloy.

[0003] 2. Description of Related Art

[0004] Since an extruded article hot-extrusion molded by an extruder is extremely hot, such extruded article has to be cooled.

[0005] In order to cool the extruded article, as shown in, for instance, FIG. 1 of Japanese Utility Model Laid-Open Publication No. Sho 60-34319, cooling fans are provided along a run-out table (conveyor) continuously provided on extrusion side of an extruder and along a cooling table continuously extending from the run-out table, so that the extruded article is forcibly air-cooled while being extruded and transferred on the cooling table.

[0006] Since air is blown by the cooling fan for forcibly air-cooling, the extruded article is gradually cooled and is less likely to be distorted and bent.

[0007] Further, since the cooling medium is air, subsequent process for the cooling medium is not necessary. Specifically, when the cooling medium is water or minute water drop dispersed in air (mist), troublesome work for collecting water is necessary after blowing the cooling medium onto the extruded article.

[0008] The run-out table has extremely elongated shape, more than fifty meters for instance, and entire width of the cooling table has approximately the same size as the length of the run-out table. Accordingly, it is so expensive to provide an equipment for collecting water on large floor surface on which the run-out table and the cooling table are installed.

[0009] The extruded article is bent when outer circumference of such extruded article is cooled in imbalanced manner while being cooled.

[0010] Accordingly, the air is uniformly blown on the outer circumference of the extruded article by the cooling fan so that the outer circumference is not cooled in imbalanced manner.

[0011] However, a part of the outer circumference is more difficult to be cooled than the other part on account of cross section of the extruded article.

[0012] For instance, FIGS. 10(A), 10(B) and 10(C) show extruded articles as a sash component made by hot-extrusion molding a material of aluminum or aluminum alloy.

[0013] An extruded article 1X shown in FIG. 10(A) has a first plate portion 2, a second plate portion 3 and a connecting portion 4, which construct approximately C-shaped cross section. Since the first plate portion 2 is thicker than the second plate portion 3 and the connecting portion 4, the first plate portion 2 is more difficult to be cooled than the second plate portion 3 and the connecting portion 4.

[0014] Another extruded article 1 Y shown in FIG. 10(B) has a hollow portion 5 and a plate portion 6, where the hollow portion 5 is more difficult to be cooled than the plate portion 6.

[0015] Still another extruded article 1Z shown in FIG. 10(C) has approximately T-shaped cross section composed of a hollow portion 7, a plate portion 8 and a connecting portion 9, where the hollow portion 7 is more difficult to be cooled than the plate portion 8 and the connecting portion 9.

[0016] Accordingly, the outer circumference of the extruded article can be cooled in imbalanced manner even when the air is uniformly blown on the outer circumference of the extruded article, thus bending the extruded article.

SUMMARY OF THE INVENTION

[0017] An object of the present invention is to overcome the above deficiencies and to provide a cooling method and a cooling equipment of an extruded article capable of cooling an extruded article having cross section of which part is more difficult to be cooled than the other part by forcible air-cooling.

[0018] A cooling method according to an aspect of the present invention includes the steps of: hot-extrusion molding an extruded article by an extruder; when a part of the outer circumference of the extruded article has a cross section more difficult to be cooled than the other part, pre-cooling the difficult-to-be-cooled part and subsequently forcibly air-cooling the extruded article; and when the extruded article has a cross section capable of approximately uniformly cooling the outer circumference thereof, forcibly air-cooling the extruded article without pre-cooling.

[0019] According to the above aspect of the present invention, when an extruded article has a cross section a part of which outer circumference is more difficult to be cooled than the other part, the difficult-to-be-cooled part is selectively pre-cooled before forcible air-cooling to lower the temperature, so that the outer circumference is not cooled in imbalanced manner.

[0020] On the other hand, when the extruded article has a cross section capable of approximately uniformly cooling the outer circumference thereof, the extruded article is forcibly air-cooled directly after being extruded.

[0021] Accordingly, an extruded article having a cross section a part of which outer circumference is more difficult to be cooled than the other part can be cooled without being bent by forcible air-cooling.

[0022] Further, since the extruded article is mainly cooled by forcible air-cooling, an after-treatment equipment of cooling medium is not necessarily provided on discharge channel of extruded article after the extruder, e.g. on a floor on which the run-out table and the cooling table are installed.

[0023] A cooling equipment for an extruded article according to another aspect of the present invention has: a main cooler provided on an extrusion side of an extruder for blowing air to an extruded article for forcibly air-cooling the extruded article; and a pre-cooler provided between the main cooler and the extruder, the pre-cooler comprising: an upper cooler for cooling the extruded article from an upper side thereof; a lower cooler for cooling the extruded article from a lower side thereof; a first side-cooler for cooling the extruded article from a first lateral side thereof; and a second side-cooler for cooling the extruded article from a second lateral side thereof, the upper cooler, the lower cooler and the first and the second side-coolers being selectively actuated in accordance with the cross section of the extruded article.

[0024] According to the above aspect of the present invention, any one or more of the upper side, the lower side, and the lateral sides of the extruded article can be selectively pre-cooled by any one of the coolers of the pre-cooler.

[0025] Accordingly, when an extruded article has a cross section a part of which outer circumference is more difficult to be cooled than the other part, the difficult-to-be-cooled part can be selectively pre-cooled.

[0026] The pre-cooled extruded article and the extruded article without being pre-cooled can be cooled by forcible air-cooling by the main cooler.

[0027] In the above cooling equipment, the respective coolers of the pre-cooler may preferably discharge a cooling medium on the outer circumference of the extruded article to cool the extruded article, the position for the upper and the lower coolers to discharge the cooling medium may preferably be changed in a direction orthogonal with extrusion direction of the extruded article, and the position for the first and the second side-coolers to discharge the cooling medium may preferably be vertically changed.

[0028] According to the above arrangement, when the cooling medium is blown on the upper side and the lower side of the extruded article by the upper and the lower coolers and on the lateral sides of the extruded article by the first and the second side-coolers, the position for blowing the cooling medium can be changed in a direction orthogonal with the extrusion direction and in vertical direction in accordance with the position and the size of the part having cross section more difficult to be cooled than the other part.

[0029] Accordingly, even when the position and the size, e.g. the position in the direction orthogonal with the extrusion direction and height dimension, of the part at which the outer circumference of the extruded article has a cross section more difficult to be cooled than the other part differ, the cooling medium can be effectively blown on the upper and lower and both lateral sides of the extruded article, thus efficiently pre-cooling the extruded article.

[0030] In the above cooling equipment, the upper cooler and the first and the second side-coolers may preferably be divided into a plurality of components along extrusion direction of the extruded article, and the divided components may preferably be capable of independent movement to a cooling position and an escape position.

[0031] According to the above arrangement, since the upper cooler, the first side-cooler and the second side-cooler can be moved to the escape position, the coolers does not interfere with the puller in starting extrusion molding by the extruder.

[0032] Further, since the coolers can be sequentially moved to the cooling position each time the puller passes after starting extrusion process for pre-cooling, the extruded article can be rapidly pre-cooled.

BRIEF DESCRIPTION OF THE DRAWINGS

[0033]FIG. 1 is a perspective view schematically showing a part of extruding equipment;

[0034]FIG. 2 is a side elevational view showing a pre-cooler;

[0035]FIG. 3 is a plan view showing the pre-cooler;

[0036]FIG. 4 is a plan view showing the pre-cooler;

[0037]FIG. 5 is a front elevational view showing a second side-cooler;

[0038]FIG. 6 is a block diagram showing a control circuit of the pre-cooler;

[0039]FIG. 7 is an illustration showing pre-cooling process of an extruded article;

[0040]FIG. 8 is another illustration showing pre-cooling process of an extruded article;

[0041]FIG. 9 is still another illustration showing pre-cooling process of an extruded article; and

[0042]FIG. 10 is a cross section showing an extruded article having cross section where a part of the outer circumference thereof is more difficult to be cooled than the other part.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT(S)

[0043]FIG. 1 is a schematic illustration showing a part of extruding equipment for extrusion-molding a metal material. The extruding equipment has an extruder 10 and an after-treatment equipment 11.

[0044] The after-treatment equipment 11 has a pre-platen cutter 12 provided on extrusion side of the extruder 10, an initial table 13 and a run-out table (conveyor) 14 consecutively provided on the extrusion side, a puller 15 reciprocating along the run-out table 5, a cooling table 16 consecutively provided adjacent to the run-out table 14 in a direction orthogonal with extrusion direction, a non-illustrated stretcher table, non-illustrated transfer table, non-illustrated saw table, non-illustrated stretchers provided on both sides of the stretcher table and a non-illustrated cutter provided on feed-out side of the saw table.

[0045] Though the initial table 13, the run-out table 14 and the cooling table 16 are illustrated as elongated rectangle for the convenience of recognizing entire arrangement, the initial table 13 and the run-out table 14 are component having a frame attached with a plurality of rollers.

[0046] The cooling table 16 has a plurality of belt conveyors 16 a. The extruded article extruded to the run-out table 14 is moved onto the belt conveyors 16 a.

[0047] Cooling fans 17 are provided above and under the run-out table 14 in a manner spaced apart with each other in longitudinal direction of the run-out table 14.

[0048] In the same manner, the cooling fans 17 are provided above and under the run-out table 14 in a manner spaced apart with each other in transfer direction of the cooling table 16.

[0049] The respective cooling fans 17 constitute a main cooler for forcibly air-cooling the extruded article on the run-out table 14 and the cooling table 16.

[0050] A pre-cooler 18 is provided on a position capable of cooling the extruded article on the initial table 13, i.e. the extruded article immediately after being extruded by the extruder 10. The pre-cooler 18 has an upper cooler 18 a, a lower cooler 18 b, a first side-cooler 18 c and a second side-cooler 18 d.

[0051] The pre-cooler 18 pre-cools the part of the outer circumference of the extruded article that is more difficult to be cooled than the other part so that the outer circumference is not cooled in an imbalanced manner while forcibly air-cooling the entire extruded article.

[0052] In other words, the pre-cooler 18 selectively cools the difficult-to-be-cooled part of the outer circumference of the extruded article in advance to lower the temperature of the portion than the temperature of the other portion.

[0053] For instance, when the upper side of the extruded article is more difficult to be cooled than the other part, the difficult-to-be-cooled part on the upper side is cooled by the upper cooler 18 a.

[0054] When the lower side of the extruded article is more difficult to be cooled than the other part, the difficult-to-be-cooled part on the lower side is cooled by the lower cooler 18 b.

[0055] When a first side of the extruded article is more difficult to be cooled than the other part, the difficult-to-be-cooled part on the first side is cooled by the first side-cooler 18 c.

[0056] When a second side of the extruded article is more difficult to be cooled than the other part, the difficult-to-be-cooled part on the second side is cooled by the second side-cooler 18 d.

[0057] When the upper and lower sides, upper and the first sides, or the upper, lower and the second sides are more difficult to be cooled than the other side, only the difficult-to-be-cooled sides are cooled.

[0058] The extruding equipment works as follows.

[0059] Initially, heated aluminum is hot-extrusion molded by the extruder 10.

[0060] The article extruded by the extruder 10 is pulled by the puller 15 while being applied with predetermined tension, which is extruded on the run-out table 14 through the initial table 13. When the extruded article moved on the initial table 13 has a cross section where a part of the outer circumference thereof is more difficult to be cooled than the other part, only the difficult-to-be-cooled part of the outer circumference is pre-cooled by the pre-cooler 18. When the outer circumference of the extruded article has a cross section capable of being cooled in approximately uniform manner, the pre-cooler 18 is not actuated.

[0061] The extrusion process is stopped when a predetermined length of extruded article is extruded and the extruded article is cut by the pre-platen cutter 12.

[0062] The cut extruded article is moved by the puller 15 or by driving the run-out table 14 to adjust the position of the head-side distal end of the extruded article.

[0063] The extruded article on the run-out table 14 is moved toward the cooling table 16 and the cooling table 16 is driven to transfer the extruded article in a direction (arrow b direction) orthogonal with extrusion direction (arrow a direction).

[0064] The cooling fans 17 are driven during the above process to cool the extruded article on the run-out table 14 and the cooling table 16 by blowing air thereonto. At this time, the air is approximately uniformly, or preferably uniformly, blown on the outer circumference of the extruded article.

[0065] Since the difficult-to-be-cooled part on the outer circumference of the extruded article is cooled in advance, the outer circumference is not cooled in an imbalanced manner. Accordingly, the extruding member is not bent by the forcible air-cooling.

[0066] The cooled extruded article is transferred to the stretcher table and is drawn by the stretcher in longitudinal direction to adjust bent of the extruded article.

[0067] Subsequently, the extruded article is transferred to the saw table by the transfer table and is cut by a cutter at a predetermined length.

[0068] Next, specific arrangement of the pre-cooler 18 will be described below with reference to FIGS. 2 to 5.

[0069] As shown in FIG. 2, the upper cooler 18 a is movable to a cooling position where a plurality of (first, second and third, for instance) upper nozzles 20 oppose to the initial table 13 (i.e. a plurality of rollers 13 a) and to an escape position where the plurality of upper nozzles 20 are located remote from the initial table 13 so as not to interfere with the puller 15.

[0070] The plurality of upper nozzles 20 are attached facing downward and are spaced apart in a direction orthogonal with the extrusion direction.

[0071] Cooling medium is blown on an upper side 1 a of the extruded article 1 by the upper nozzle 20.

[0072] Specific arrangement for attaching the upper nozzle 20 will be described below with reference to FIGS. 2 and 3.

[0073] A plurality of (three, for instance) bases 22 are provided on a base plate 21 adjacent to the initial table 13 being spaced apart in extrusion direction.

[0074] A first shaft 23 and a second shaft 24 are attached to the respective bases 22 in parallel with extrusion direction.

[0075] The first shaft 23 and the second shaft 24 are rotatable and a base end of a first arm 25 and a second arm 26 are respectively fixed thereto. Distal ends of the first arm 25 and the second arm 26 are rotatably connected to a moving shaft 27 by a third shaft 28 and a fourth shaft 29, thereby constructing a parallel four-node link 30.

[0076] A horizontal member 31 is fixed to the moving shaft 27. The respective horizontal members 31 are elongated in extrusion direction. A plurality of pipes (first, second and third, for instance) 32 are attached to the horizontal member 31 while being spaced apart in a direction orthogonal with extrusion direction and the upper nozzle 20 is attached to the respective pipes 32 facing downward in extrusion direction.

[0077] The first shaft 23 is rotated by an electric motor 33.

[0078] The upper cooler 18 a is separated into plural components in extrusion direction, which are independently moved to the cooling position and the escape position.

[0079] Accordingly, by rotating the first shaft 23 in forward direction, the horizontal member 31 moves to the upper position of the initial table 13 as shown in solid line in FIG. 2 and the upper nozzle 20 moves to the cooling position.

[0080] When the second shaft 23 is reversely rotated by the motor 33, the horizontal member 31 moves to a position shown in imaginary line in FIG. 2 where the horizontal member 31 is located remote from the initial table 13 and the upper nozzle 20 moves to the escape position.

[0081] Three horizontal members 31 are spaced apart in extrusion direction and the respective horizontal members 31 can be independently moved to the upper position of the initial table 13 and the position remote from the initial table 13, so that the upper nozzles 20 attached to the respective horizontal members 31 are independently moved to the cooling position and the escape position.

[0082] When the extrusion process is started, the respective horizontal members 31 are moved to the position remote from the initial table 13 to prevent interference with the puller 15.

[0083] Each time the puller 15 is moved in the extrusion direction to pass the horizontal member 31 after starting extrusion, the horizontal member 31 is sequentially moved to the upper position of the initial table 13 to locate the upper nozzle 20 at the cooling position to pre-cool the upper side of the extruded article.

[0084] Accordingly, the extruded article can be cooled at an earlier stage as compared to an arrangement where the horizontal member 31 is constructed as a unitary component.

[0085] As shown in FIG. 2, the lower cooler 18 b has a lower nozzle 40 capable of movement in a direction (arrow c direction) orthogonal with the extrusion direction under the initial table 13. The lower nozzle 40 faces upward to blow the cooling medium on a lower side 1 b of the extruded article 1 on the initial table 13.

[0086] Specifically, as shown in FIGS. 2 and 4, a rod 42 a of rod-type movable body 42 is fixed on a plurality of platforms 41 spaced apart in the extrusion direction, the rods 42 a facing in a direction orthogonal with extrusion direction. An elongated moving member 43 is attached to tubes 42 b on the rod 42 a, the member 43 extending in the extrusion direction and pipes 44 are attached to the moving member 43, where the lower nozzle 40 is attached to the pipes 44 facing upward being spaced apart in the extrusion direction.

[0087] The lower nozzle 40 is located between rollers 13 a of the initial table 13 and blows cooling medium on a lower side 1 b of the extruded article 1 from between the rollers 13 a.

[0088] The rod-type movable body 42 is electrically driven. For instance, a pinion is rotated by an electric motor provided on the tube 42 b and the pinion is meshed with a rack provided on the rod 42 a and the tube 42 b is slid relative to the rod 42 a by rotating the pinion with the electric motor.

[0089] Incidentally, the moving body 43 may be divided into plural components to divide the lower cooler 18 b in plural in extrusion direction.

[0090] The first side-cooler 18 c and the second side-cooler 18 d are of the same configuration, where a horizontally-extending side nozzle 50 is moved (elevated and lowered) to an escape position at which the side nozzle 50 does not interfere with the puller 15 and to a cooling position at which the lower nozzle 50 opposes a first side 1 c and a second side 1 d of the extruded articles. The nozzle 50 vertically (in arrow d direction in FIG. 2) moves at the cooling position.

[0091] Specifically, as shown in FIGS. 2, 3 and 5, a plurality of (three, for instance) elongated movable body 51 is provided on both sides of the initial table 13 being spaced apart in extrusion direction.

[0092] The respective movable bodies 51 have a plurality of slide shafts 52, the respective slide shafts 52 being vertically and slidably fitted in a vertical guide 53 provided on the base plate 21, so that the respective movable bodies 51 are capable of elevation.

[0093] A pipe 54 is attached to the respective movable bodies 51 facing in the extrusion direction. The plurality of side nozzles 50 are attached to the pipe 54 facing sideward and being spaced apart in longitudinal direction of the extruded article.

[0094] A rack 55 is vertically fixed on the respective movable bodies 51. A pinion 56 meshed with the rack 55 is rotated by an electric motor 57.

[0095] Accordingly, when the pinion 56 is rotated by the electric motor 57, the movable body 51 is vertically moved through the rack 55, so that the side nozzle 50 is moved to the cooling position and the escape position and is vertically moved at the cooling position to adjust the height of the side nozzle 50.

[0096] Since the plurality of movable bodies 51 are elevatably attached while being spaced apart in the extrusion direction, the movable body 51 can be sequentially moved to the cooling position each time the puller 15 passes the movable body 51 during the extrusion process, so that the timing for starting to cool the lower side of the extruded article can be set earlier.

[0097] In other words, the first side-cooler 18 c and the second side-cooler 18 d are divided into plural components in extrusion direction and are independently moved to the cooling position and the escape position.

[0098] Next, actuation control circuit of the pre-cooler 18 will be described below with reference to FIG. 6.

[0099] When a discharge channel 61 of a cooling medium source, cooling water pump 60 for instance, is opened by an electromagnetic valve 62, the cooling medium is fed to the three upper nozzles 20, the lower nozzle 40 and the side nozzles 50 through the pipes 32, 44 and 54 in a pressurized manner.

[0100] The electromagnetic valve 62 is held at a closed position by a spring force and is set at an open position when a solenoid 63 is energized.

[0101] The cooling medium is discharged only from a nozzle connected with the opened electromagnetic valve 62.

[0102] The energization of the solenoid 63 is controlled by a controller 64.

[0103] The controller 64 controllably drives the electric motor 33, the electric motor 42 c of the rod-type movable body 42 and the electric motor 57.

[0104] In the controller 64, a nozzle and the position of the nozzle in accordance with the cross section based on the type and number of the extruded article is stored as a cooling setting information.

[0105] When a worker checks the existence of the difficult-to-be-cooled part on the outer circumference of the extruded article and determined the existence in conducting the extrusion process, the worker selects the nozzle and the position of the nozzle that discharges the cooling medium in accordance with the cross section of the extruded article and the solenoid 63 of the electromagnetic valve 62 corresponding to the cooling setting information stored in the controller 64 in advance is energized, so that the electric motor 42 c and 57 are driven to cool only the difficult-to-be-cooled part on the outer circumference of the extruded article.

[0106] For instance, when an extruded article 1X of the cross section shown in FIG. 10(A) is to be molded so that the first plate portion 2 faces the first side-cooler 18 c as shown in FIG. 7, the electric motor 57 of the first side-cooler 18 c is driven and the side nozzle 50 is set at the cooling position, where the height of the side nozzle 50 is adjusted to a predetermined height H₁ at which the side nozzle 50 opposes the vertical center of the first plate portion 2. The above height refers to the height from the upper side of the initial table 13.

[0107] The operation is sequentially conducted for each movable body 51 before which the puller 15 has passed.

[0108] When the height of the side nozzle 50 is set at the predetermined height of H₁, or after the puller 15 has passed, the solenoid 63 of the electromagnetic valve 62 connected with the side nozzle 50 is energized to set at the open position.

[0109] Accordingly, the cooling medium is blown only on the first plate portion 2 that is difficult to be cooled on the extruded article 1, thereby pre-cooling the first plate portion 2.

[0110] When an extruded article 1Y having cross section shown in FIG. 10(B) is extruded so that the hollow portion 5 opposes to the first side-cooler 18 c, the height of the side nozzle 50 is set at a predetermined height H₂ at which the side nozzle 50 opposes to the vertical center of the hollow portion 5.

[0111] When an extruded article 1Z having cross section shown in FIG. 10(C) is extruded so that the hollow portion 7 opposes to the first side-cooler 18 c, since the upper side 7 a, the lower side 7 b and the first side 7 c are more difficult to be cooled than the other part, the respective sides are cooled by the upper cooler 18 a, the lower cooler 18 b and the first side-cooler 18 c.

[0112] The first side-cooler 18 c works in the above-described manner, and the height of the side nozzle 50 thereof is set at a predetermined height H₃ at which the side nozzle 50 opposes to the vertical center of the first side 7 c of the hollow portion 7.

[0113] The solenoid 63 of the electromagnetic valve 62 connected with the upper nozzle 20 which is the most adjacent to the first side (the upper nozzle 20 opposing to the center of the upper side 7 a of the hollow portion 7 in a direction orthogonal with the extrusion direction) is energized.

[0114] The electric motor 42 c of the lower cooler 18 b is driven to set the lower nozzle 40 at a position opposing to the center of the lower side 7 b of the hollow portion 7 in a direction orthogonal with the extrusion direction.

[0115] The solenoid 63 of the electromagnetic valve 62 connected with the lower nozzle 40 is energized to set the valve 62 at an open position.

[0116] According to the above arrangement, the upper nozzle 20, the side nozzle 50 and the lower nozzle 40 oppose approximately to the center of the difficult-to-be-cooled part, so that the cooling medium can be efficiently blown on the entire are of the difficult-to-be-cooled part.

[0117] As described above, the extruded article of which a part of the outer circumference is selectively cooled is forcibly air-cooled while being moved on the run-out table 14 and being transferred by the cooling table 15.

[0118] The temperature of the outer circumference is approximately uniformly lowered during the forcible air-cooling and is not cooled in imbalanced manner, thereby preventing bent of the extruded article.

[0119] When a worker judges that there is no difficult-to-be-cooled part on a part of the outer circumference (i.e. that the extruded article has a cross section capable of approximately uniformly cooling the outer circumference thereof), the pre-cooler 18 is not actuated. At this time, the upper cooler 18 a, the first and the second side-coolers 18 c and 18 d are at the escape position.

[0120] The extruded article is forcibly air-cooled while moving on the run-out table 14 and being transferred on the cooling table 15.

[0121] At this time, the temperature of the outer circumference of the extruded article is approximately uniformly cooled and is not cooled in an imbalanced manner, thereby preventing bent of the extruded article.

[0122] Though three upper nozzles 20 are provided in a direction orthogonal with the extrusion direction and the cooling medium is selectively discharged from one of the upper nozzles 20, the upper nozzle 20 may be arranged to move in a direction orthogonal with the extrusion direction.

[0123] Similarly, a plurality of the lower nozzles 40 may be provided in a direction orthogonal with the extrusion direction and the cooling medium may be selectively discharged from one of the lower nozzles 40.

[0124] A plurality of the side nozzles 50 may be vertically provided and the cooling medium may be selectively discharged from one of the side nozzles 50.

[0125] In other words, any arrangement is possible for the upper and lower coolers 18 a and 18 b as long as the position for discharging the cooling medium can be changed in a direction orthogonal with the extrusion direction.

[0126] Any arrangement is possible for the first and the second side-coolers 18 c and 18 d as long as the position for discharging the cooling medium can be vertically changed. The cooling medium may be cooling water and water drop dispersed in the air (mist) as well as air.

[0127] The amount and width of the cooling medium blown from the respective nozzles may be controllably changed. For instance, the amount of the cooling medium is controlled by changing flow rate and feed pressure.

[0128] According to the present invention, when an extruded article has a cross section a part of which outer circumference is more difficult to be cooled than the other part, the difficult-to-be-cooled part is selectively pre-cooled before forcible air-cooling to lower the temperature, so that the outer circumference is not cooled in imbalanced manner and the extruded article is not bent during forcible air-cooling.

[0129] An extruded article having cross section of which outer circumference is capable of being cooled in approximately uniform manner is directly and forcibly air-cooled after being extruded.

[0130] Accordingly, an extruded article having a cross section a part of which outer circumference is more difficult to be cooled than the other part can be cooled without being bent by forcible air-cooling.

[0131] Further, since the extruded article is mainly cooled by forcible air-cooling, an after-treatment equipment of cooling medium is not necessarily provided on discharge channel of extruded article after the extruder, e.g. on a floor on which the run-out table and the cooling table are installed.

[0132] Any one of the upper side, the lower side, and lateral sides can be selectively pre-cooled by any one of the coolers of the pre-coolers 18.

[0133] Accordingly, when an extruded article has a cross section a part of which outer circumference is more difficult to be cooled than the other part, the difficult-to-be-cooled part can be selectively pre-cooled.

[0134] The pre-cooled extruded article and the extruded article without being pre-cooled can be cooled by forcible air-cooling by the main cooler.

[0135] When the cooling medium is blown on the upper and lower sides and lateral sides of the extruded article by the upper and lower coolers 18 a and 18 b or the first and second side-coolers 18 c and 18 d, the position for blowing the cooling medium can be changed in a direction orthogonal with extrusion direction or in vertical direction in accordance with the position or size of the portion at which the outer circumference of the extruded article has a cross section more difficult to be cooled than the other part.

[0136] Accordingly, even when the position and the size, e.g. the position in the direction orthogonal with the extrusion direction and height dimension, of the portion at which the outer circumference of the extruded article has a cross section more difficult to be cooled than the other part differs, the cooling medium can be effectively blown on the upper and lower and both lateral sides of the extruded article, thus efficiently pre-cooling the extruded article.

[0137] Since the upper cooler 18 a, the first side-cooler 18 c and the second side-cooler 18 d can be moved to the escape position, the coolers do not interfere with the puller in starting extrusion molding by the extruder 10.

[0138] Since the coolers can be sequentially moved to the cooling position each time the puller passes after starting extrusion process for pre-cooling, the extruded article can be rapidly pre-cooled. 

What is claimed is:
 1. A cooling method, comprising the steps of: hot-extrusion molding an extruded article by an extruder; when a part of the outer circumference of the extruded article has a cross section more difficult to be cooled than the other part, pre-cooling the difficult-to-be-cooled part and subsequently forcibly air-cooling the extruded article; and when the extruded article has a cross section capable of approximately uniformly cooling the outer circumference thereof, forcibly air-cooling the extruded article without pre-cooling.
 2. A cooling equipment for an extruded article, comprising: a main cooler provided on an extrusion side of an extruder for blowing air to an extruded article for forcibly air-cooling the extruded article; and a pre-cooler provided between the main cooler and the extruder, the pre-cooler comprising: an upper cooler for cooling the extruded article from an upper side thereof; a lower cooler for cooling the extruded article from a lower side thereof; a first side-cooler for cooling the extruded article from a first lateral side thereof; and a second side-cooler for cooling the extruded article from a second lateral side thereof, the upper cooler, the lower cooler and the first and the second side-coolers being selectively actuated in accordance with the cross section of the extruded article.
 3. The cooling equipment according to claim 2, wherein the respective coolers of the pre-cooler discharge a cooling medium on the outer circumference of the extruded article to cool the extruded article, wherein the position for the upper and the lower coolers to discharge the cooling medium can be changed in a direction orthogonal with extrusion direction of the extruded article, and wherein the position for the first and the second side-coolers to discharge the cooling medium can be vertically changed.
 4. The cooling equipment according to claim 2, wherein the upper cooler and the first and the second side-coolers are divided into a plurality of components along extrusion direction of the extruded article, and the divided components are capable of independent movement to a cooling position and an escape position. 